Near-infrared photometry of the young open clusters NGC 1893 and Berkeley 86

We present photometry in the J and K near-infrared bands for two regions ce ntered on the young open clusters NGC 1893 and Berkeley 86. We study 700 st ars down to K = 17 in the field of NGC 1893, and about 2000 stars in the he ld of Berkeley 86 down to K similar to 16.5, for which near-infrared photom etry was insofar not available. Coupling J-K data with UBV photometry taken from literature, we produce reddening corrected colour-magnitude diagrams. We find that our data are consistent with previous determinations: the clu sters are roughly coeval with an age between 4 and 6 million years. The mea n reddening (measured as E(J-K)) values turn out to be 0.35 and 0.50 for NG C 1893 and Berkeley 86, respectively. Using colour-colour plots we discuss the presence of candidate pre-main seq uence stars showing infrared excess. Candidates are found in both cluster r egions, confirming the young age of these clusters.